The present invention relates to a recording information management method for a disk of a zone CLV (every time the recording track zone changes, the angular velocity changes; the angular velocity does not change in a zone) or a modified CAV (the angular velocity changes stepwise depending on the recording track position; the angular velocity does not change in each step) type.
In zone CLV (to be referred to as ZCLV hereinafter; CLV is the abbreviation of Constant Linear Velocity), the angular velocity is controlled to be constant in each zone (CAV; Constant Angular Velocity). When the recording track zone changes, the rotation speed (angular velocity) changes so that the average recording density in each zone becomes almost constant. That is, in ZCLV, CAV control is performed in each zone, and when the zone changes, the angular velocity changes accordingly.
In zone CAV (ZCAV) or modified CAV (MCAV), CAV control is performed in all zones, and when the zone changes, the read/write modulation rate changes.
For a ZCLV disk, the rotation servo of the disk need not be switched in each zone because the angular velocity does not change in each zone so that access properties similar to those of a CAV disk can be obtained in each zone. In ZCLV, when the zone changes, the angular velocity is changed (reduced in the outer zone of the disk). With this operation, a decrease in recording density on the outer side of the disk is prevented by maintaining a roughly constant average linear velocity on both inner and outer sides of the disk. Therefore, in the ZCLV disk, a memory capacity similar to that of a CLV disk (within the same zone) and access properties similar to those of a CAV disk can be obtained.
All writable disks of the CLV, CAV, and ZCLV schema require management information representing the size and position of a file recorded in the disk. This management information is generally called a file allocation table (FAT) and a set of pieces of management information are recorded in a specific area (one or two areas; in the case of two areas, one area is used as a backup area) of the disk.
The FAT is appropriately referred to when data is to be read out from or written in the disk. In the CAV disk (e.g., a hard disk), the disk rotation speed is always constant. The rotation servo of the disk need not be switched (the rotation speed of a spindle motor need not be changed) even when an FAT reference operation is frequently performed during data reading/writing, and reading/writing is performed smoothly.
In the ZCLV disk, however, the disk rotation speed of the data read/write area is different from that of the FAT area. For this reason, the rotation speed of the spindle motor must be changed every time in which the FAT is referred, and the read/write access speed decreases (since the rotation servo is switched every time the optical pickup reciprocates between constant rotation speed zones, a time lag until the servo settles to a target rotation value is generated every time the zone changes).